Automatic Traffic Lights Control
You will mostly see this kind of traffic light in Vietnam, though i don't know if there are any in other countries...
I made this circuit with an Arduino Mega 2560. Pin 40 to 53 are used to power the two 7 segments displays, while pin 10, 11 and 12 are used to power the three LEDs.
Don't forget to place a resistor (at least 220 ohms) between those 3 LEDs, or they will burn to a crisp!
(I actually forgot to place resistors, but luckily they just lit really bright, not burnt XD)